---
name: "prioqueue"
section: "3tcl"
platform: "linux"
package: "tcllib"
version: "2.0+dfsg-4"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/prioqueue"
---

# prioqueue(3tcl)

Create and manipulate prioqueue objects

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```

## NAME

struct::prioqueue - Create and manipulate prioqueue objects

## SYNOPSIS

package require **Tcl 8.5 9**

package require **struct::prioqueue ?1.5?**

**::struct::prioqueue** ?**-ascii\|-dictionary\|-integer\|-real**? ?*prioqueueName*?

*prioqueueName* **option** ?*arg arg ...*?

*prioqueueName* **clear**

*prioqueueName* **remove** *item*

*prioqueueName* **destroy**

*prioqueueName* **get** ?*count*?

*prioqueueName* **peek** ?*count*?

*prioqueueName* **peekpriority** ?*count*?

*prioqueueName* **put** *item prio* ?*item prio ...*?

*prioqueueName* **size**

```

```

## DESCRIPTION

This package implements a simple priority queue using nested tcl lists.

The command **::struct::prioqueue** creates a new priority queue with default priority key type *-integer*. This means that keys given to the **put** subcommand must have this type.

This also sets the priority ordering. For key types *-ascii* and *-dictionary* the data is sorted in ascending order (as with **lsort** *-increasing*), thereas for *-integer* and *-real* the data is sorted in descending order (as with **lsort** *-decreasing*).

Prioqueue names are unrestricted, but may be recognized as options if no priority type is given.

- **::struct::prioqueue** ?**-ascii\|-dictionary\|-integer\|-real**? ?*prioqueueName*?

  The **::struct::prioqueue** command creates a new prioqueue object with an associated global Tcl command whose name is *prioqueueName*. This command may be used to invoke various operations on the prioqueue.  It has the following general form:

- *prioqueueName* **option** ?*arg arg ...*?

  **option** and the *arg*s determine the exact behavior of the command.  The following commands are possible for prioqueue objects:

- *prioqueueName* **clear**

  Remove all items from the prioqueue.

- *prioqueueName* **remove** *item*

  Remove the selected item from this priority queue.

- *prioqueueName* **destroy**

  Destroy the prioqueue, including its storage space and associated command.

- *prioqueueName* **get** ?*count*?

  Return the front *count* items of the prioqueue (but not their priorities) and remove them from the prioqueue. If *count* is not specified, it defaults to 1.  If *count* is 1, the result is a simple string; otherwise, it is a list.  If specified, *count* must be greater than or equal to 1.  If there are no or too few items in the prioqueue, this command will throw an error.

- *prioqueueName* **peek** ?*count*?

  Return the front *count* items of the prioqueue (but not their priorities), without removing them from the prioqueue. If *count* is not specified, it defaults to 1.  If *count* is 1, the result is a simple string; otherwise, it is a list.  If specified, *count* must be greater than or equal to 1.  If there are no or too few items in the queue, this command will throw an error.

- *prioqueueName* **peekpriority** ?*count*?

  Return the front *count* items priority keys, without removing them from the prioqueue. If *count* is not specified, it defaults to 1.  If *count* is 1, the result is a simple string; otherwise, it is a list.  If specified, *count* must be greater than or equal to 1.  If there are no or too few items in the queue, this command will throw an error.

- *prioqueueName* **put** *item prio* ?*item prio ...*?

  Put the *item* or items specified into the prioqueue. *prio* must be a valid priority key for this type of prioqueue, otherwise an error is thrown and no item is added.  Items are inserted at their priority ranking. Items with equal priority are added in the order they were added.

- *prioqueueName* **size**

  Return the number of items in the prioqueue.

## BUGS, IDEAS, FEEDBACK

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category *struct :: prioqueue* of the *Tcllib Trackers* \[http://core.tcl.tk/tcllib/reportlist\]. Please also report any ideas for enhancements you may have for either package and/or documentation.

When proposing code changes, please provide *unified diffs*, i.e the output of **diff -u**.

Note further that *attachments* are strongly preferred over inlined patches. Attachments can be made by going to the **Edit** form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar.

## KEYWORDS

ordered list, prioqueue, priority queue

## CATEGORY

Data structures

## COPYRIGHT

```
Copyright (c) 2003 Michael Schlenker <mic42@users.sourceforge.net>
```